'use strict';
import { useEffect, useRef } from 'react';

import type { Maybe } from '../common';
import { logger } from '../common';
import type { InstanceOrElement, SharedValue } from '../commonTypes';
import type {
  AnimatedRef,
  ReanimatedScrollEvent,
  RNNativeScrollEvent,
} from './commonTypes';
import type { EventHandlerInternal } from './useEvent';
import { useEvent } from './useEvent';
import { useSharedValue } from './useSharedValue';

const NOT_INITIALIZED_WARNING =
  'animatedRef is not initialized in useScrollOffset. Make sure to pass the animated ref to the scrollable component to get scroll offset updates.';

const NATIVE_SCROLL_EVENT_NAMES = [
  'onScroll',
  'onScrollBeginDrag',
  'onScrollEndDrag',
  'onMomentumScrollBegin',
  'onMomentumScrollEnd',
] as const;

/**
 * Lets you synchronously get the current offset of a scrollable component.
 *
 * @param animatedRef - An [animated
 *   ref](https://docs.swmansion.com/react-native-reanimated/docs/core/useAnimatedRef)
 *   attached to a scrollable component.
 * @returns A shared value which holds the current scroll offset of the
 *   scrollable component.
 * @see https://docs.swmansion.com/react-native-reanimated/docs/scroll/useScrollOffset
 */
export function useScrollOffset<TRef extends InstanceOrElement>(
  animatedRef: Maybe<AnimatedRef<TRef>>,
  providedOffset?: SharedValue<number>
): SharedValue<number> {
  const internalOffset = useSharedValue(0);
  const offset = useRef(providedOffset ?? internalOffset).current;

  const eventHandler = useEvent<RNNativeScrollEvent>(
    (event: ReanimatedScrollEvent) => {
      'worklet';
      offset.value =
        event.contentOffset.x === 0
          ? event.contentOffset.y
          : event.contentOffset.x;
    },
    NATIVE_SCROLL_EVENT_NAMES
    // Read https://github.com/software-mansion/react-native-reanimated/pull/5056
    // for more information about this cast.
  ) as unknown as EventHandlerInternal<ReanimatedScrollEvent>;

  useEffect(() => {
    if (!animatedRef) {
      return;
    }

    return animatedRef.observe((tag) => {
      if (!tag) {
        logger.warn(NOT_INITIALIZED_WARNING);
        return;
      }

      eventHandler.workletEventHandler.registerForEvents(tag);
      return () => {
        eventHandler.workletEventHandler.unregisterFromEvents(tag);
      };
    });
  }, [animatedRef, eventHandler]);

  return offset;
}